Miniaturized Reference Electrodes Based on Ag/AgiX Internal Reference Elements. I. Manufacturing and Performance

Abstract

We report the manufacturing and performance of miniaturized reference electrodes (MREs) of wide applicability, with highly stable potential in both aqueous and organic media, and minimal low sensitivity to Cl− ions (−3.4 mV/log a) and pH (0.082 mV/pH). These MREs are based on an Ag/AgiX internal reference element (IRE), where AgiX is a low solubility silver salt (X=Cl−, SCN−, or . IREs are imbedded in a photopolymerized acrylic hydrogel, with no solid salt supply present in the system. Polymer matrices were tested for swelling/dissolution, and for loss of both electrolyte and silver ions. MREs have a potential stability of ±0.5 mV over 30 h, and a low temperature coefficient of 0.15 mV K−1 (in the range of 281.8–298.6 K).